Water isotopes in precipitation:. data/model comparison for present-day and past climates

摘要: Abstract Variations of HDO and H2 18 O concentrations are observed in precipitation both on a geographical temporal basis. These variations, resulting from successive isotopic fractionation processes at each phase change water during its atmospheric cycle, well documented through the IAEA/WMO network. Isotope are, middle high latitudes, linearly related to annual mean temperature site. Paleoclimatologists have used this relationship infer paleotemperatures isotope paleodata extractable ice cores, deep groundwater other such sources. For application be valid, however, spatial must also hold time given location as undergoes series climatic changes. Progress modeling aimed examining evaluating assumption has been recently reviewed (Jouzel et al., 1997) with focus polar regions and, more specifically, Greenland. We extend review comparing results two different AGCMs (NASA/GISS ECHAM) examining, global perspective, validity above assumption, i.e. equivalence isotope–temperature relationships. confirm dominating role local changes paleo signal most regions. However, exact calibration valuable paleothermometer is biased by, for example, seasonality factors. forced models by boundary conditions mild-holocene 6 kyr BP which only slightly differs today's climate. The response weak forcing quite heterogeneous. robust common intensification hydrological cycle low latitudes therefore, isotopically depleted tropics subtropics. examine recent progress made modeling: between prevailing moisture source deuterium excess that precipitation.